THE PLANT GROWTH PROMOTOR AUXIN (IAA) PRODUCTION ABILITY IN Arthrospira massartii – ARH STRAIN ISOLATED FROM VIETNAM AND ITS POTENTIAL APPLICATIONS

Cyanobacteria are a group of photoautotrophic prokaryotes which have the ability to biosynthesize plant growth regulators, especially Indole-3-acetic acid (IAA), and have not been focused on research yet in Vietnam. In this study, Arthrospira massartii (ARH strain) - a planktonic cyanobacterial strain isolated from a freshwater lake in Hue City, Thua Thien Hue Province, Vietnam - is showing good growth ability under an artificial culture condition with the maximum cell density of 58.44 x 104 cells/mL and the highest total IAA content of 18.62 µg/mL. This ARH strain also showed potential for IAA production even in the absence of L-tryptophan in the culture medium. The content of L-tryptophan supplemented with 600 µg/mL was the best for extracellular and intracellular IAA biosynthesis in Arthrospira massartii – ARH strain. ARH cyanobacterial extract has also shown to have a positive effect on the budding shoot multiplication and rooting of tissue-cultured ginger plants. Research results have demonstrated the potential to apply the extract of cyanobacteria Arthrospira massartii – ARH in the field of plant tissue culture to partially replace plant growth promoters and cultivation stimulants.